1. Field of the Invention
The present invention relates to an analysis system and method for an unknown substance, and particularly to a gas analysis system and method that automatically detects the species and corresponding concentration of unknown substances using the absorption spectrum thereof.
2. Description of the Related Art
The monitor of species and concentration of gas and quality of air has become an important issue in the area of environmental security and hygiene. For example, if process piping is leaking, the species and concentration of the leaked gas will seriously affect the quality of process, and operators may be endangered. Conventional gas detection means uses a specified sensor to analyze specified gas. Since it cannot analyze all unknown substances (gas), it has limited application in industry.
Another conventional method uses a Fourier transform infrared (FTIR) spectrometer to analyze species of molecule. The FTIR spectrometer includes an IR source, an interferometer, an optics system and a detector, and obtains the interferogram of the molecule according to the interference theorem of light. The interferogram is a relational diagram of the intensity of IR source and time. Then, the interferogram can be transformed into a frequency-based absorption spectrum using Fourier transformation according to a reference (background) interferogram, and the chemical species and concentration of the molecule can be recognized using the spectral lines of the absorption spectrum and Bill's law.
When the dipole distance between molecules is changed and the energy provided by the IR source equals the transition energy between the molecules, the molecules may absorb the IR source and generate the IR absorption spectrum. The IR absorption spectrum is different from the molecules, and it is an effective tool to recognize and determine the chemical species and concentration of the molecules.
However, all of the gas analysis methods are operated manually, and make comparisons with sample spectra one by one. If the gas is complex, and if unknown substances appear in the gas, the analysis is time-consuming. Further, the obtained species and concentration are only checked for fulfillment of regulation, and there are no further applications thereto.